The art has described microemulsion concentrates for active ingredients. See, for example, Narayanan U.S. Pat. No. 6,045,816, issued Apr. 4, 2000 “Water-Based Microemulsion of a Pyrethroid”; U.S. Pat. No. 6,187,715, issued Feb. 13, 2001 “Water Based Microemulsions of a Lower Alkyl Ester of Quinoxalinyl Herbicide”; U.S. Pat. No. 6,251,416—issued Jun. 26, 2001 “Water-Based Microemulsion of a Pyrethroid”; U.S. Pat. No. 6,541,516—issued Apr. 1, 2003 “Water Miscible Emulsions of Pyrethroid Insecticides or Triazole Fungicides”.
Technical Field of the Invention
The present invention relates to a matrix composition capable of forming an emulsion/micro-emulsion/dispersion comprising an emulsifiable matrix, essentially free of alkyl pyrrolidone and alkoxylated alcohol, comprising: (i) a long chain substituted amide; (ii) a surface active agent; and (iii) optionally, an organic diluent. The matrix composition optionally can further comprise a water insoluble film-forming polymer. More particularly, the present invention relates to the matrix composition which dissolves hydrophobic active to form a concentrate. The concentrate on dilution with water forms an emulsion/micro-emulsion or dispersion.
The hydrophobic active useful in the practice of the invention can be selected from agricultural fertilizers, nutrients, plant growth accelerants, herbicides, plant growth regulators, insecticides, bactericides, fungicides, nematocides, fumigants, light stabilizers, UV absorbers, synthetic hydrocarbons, radical scavengers, resins, natural waxes, fragrances, organic solvents and monomers for polymers, and/or disinfectants and/or combinations thereof.
Further, the matrix of the present invention is free of alkyl pyrrolidones and alkoxylated alcohols. The present invention provides a composition that finds application in providing efficient delivery of hydrophobic actives alone or in combination with film forming polymers suitable for film forming applications such as wood protection, plant protection and the like.
Description of the Prior Art
Delivery of hydrophobic actives is always a challenging task. Particularly, hydrophobic actives include herbicides, insecticides, fungicides, light stabilizers, UV absorbers, synthetic hydrocarbons, radical scavengers, resins, natural waxes, fragrances, disinfectants and/or combinations. They are most preferably applied in the form of aqueous emulsions, solutions or suspensions. Occasionally, they may also be applied in the form of a dust wherein the active ingredient is adsorbed onto or mixed with a finely divided inert carrier material, such as, china clay, or the like. With such powdered or dust compositions, drift due to wind is a problem and consequently, liquid formulations are preferred.
One of the basic problems in delivering hydrophobic actives is the fact these chemicals often exhibit extreme insolubility in water. This results in their having to be dissolved either in organic solvents or utilized in the form of emulsions or suspensions. With respect to the use of organic solvents, these are generally disadvantageous from an environmental and cost viewpoint. Particularly, such organic chemicals may exhibit toxicity or side-effects which may be adverse to the effect of the actives/chemical itself or to its subsequent application. This toxicity may also be disadvantageous with respect to handling and also may adversely affect the environment.
Another problem is associated with the use of certain types of polymers which exhibit film-forming properties and when dissolved in a solvent, can be applied for the purpose of providing a coating on a substrate. Usually, the film-forming polymer in the solvent is applied to the particular substrate to be coated, and the solvent is allowed to evaporate or removed leaving a film of the polymer. Generally, however, such film-forming polymers arc soluble only in organic solvents. The use of such organic solvents generally is undesirable since they exhibit environmentally adverse properties, are often hazardous or flammable, and are generally expensive. In order to avoid the environmentally adverse effects of such organic solvents as well as to reduce the cost involved with using such solvents, rather complicated solvent recovery procedures must be used.
Various attempts are made to provide emulsified or suspension formulations, difficulties are encountered with respect to providing a desirably high concentration of the hydrophobic active ingredients particularly agricultural, herbicides, pesticides etc. Emulsions (or macroemulsions) are usually unstable. The suspended droplets will eventually agglomerate and the dispersed phase will phase separate. Emulsion droplet sizes are much larger, typically one micron or more, resulting in a cloudy or milky dispersion. The nature of an emulsion may depend on the order of mixing of the ingredients and the amount of energy put into the mixing process. The final microemulsion state will not depend on order of mixing, and energy input only determines the time it will take to reach the equilibrium state. There have been limited efforts to develop.
Thus, when such hydrophobically actives/chemicals are formulated into a macroemulsion (sometimes referred to herein as an emulsion), it is difficult to maintain the emulsified state. This, in turn, creates problems in maintaining a uniform formulation, particularly, when the formulation is diluted with water for application to the plants, woods or as coatings.
The development of microemulsion technology has enabled formation of improved dispersions for some materials. Microemulsions are thermodynamically stable dispersions of one liquid phase into another, stabilized by an interfacial film of surfactant. This dispersion may be either oil-in-water or water-in-oil. Microemulsions are typically clear solutions, as the droplet diameter is approximately 100 nanometers or less. The interfacial tension between the two phases is extremely low.
U.S. Pat. No. 5,317,042 disclosed a clear stable, efficacious aqueous microemulsion of a pyrethroid insecticide, alone, or in a complex mixture, obtained by mixing the insecticide with an inert matrix composition containing a defined mixture of nonionic surfactant to form a microemulsion concentrate, and diluting with water. The inert matrix composition consisted of a predetermined mixture of nonionic surfactants which also included nonylphenol ethoxylate with HLB>6. However, the presence of nonylphenol ethoxylate in the formulation may be considered detrimental in some cases.
Further, U.S. Pat. No. 5,425,955 discloses emulsion concentrates of water-insoluble film-forming polymers which can be utilized to form water-resistant films of active ingredients, such as, agriculturally active chemicals. Methods for preparation and use of the emulsion concentrates are disclosed.
Similarly, U.S. Pat. No. 5,766,615 discloses compositions that are composed of the water-insoluble polymers, a surfactant, and a long chain alkylpyrrolidone and which form clear stable microemulsion or solution of the insoluble polymer is obtained on the addition of water.
Most of the prior art cited references suggested the use of alkyl pyrrolidone solvent as one of the major components of the matrix. However, in recent years more stress has been on environmentally safe or EPA approved chemicals that can be safely applied to agricultural fields.
U.S. Pat. No. 5,283,229 discloses the combination of alkyl pyrrolidones and dialkyl amides. The invention particularly relates to a concentrate which is composed of an agriculturally active chemical, a surfactant, and a solvent composed of first and second components. The first component is selected from the group consisting of N-methylpyrrolidone, ethylene carbonate, propylene carbonate, butylene carbonate, N-N,dimethylimidazolone, dimethyl formamide and dimethylacetamide, dimethylsulfoxide, and mixtures thereof and the second component is selected from the group consisting of octylpyrrolidone, dodecylpyrrolidone, N-2-ethylhexylpyrrolidone, and mixtures thereof.
However, the microemulsion concentrates of the above related patents require a large amount of N-alkyl pyrrolidones including N-methyl pyrrolidone for increased loading of the active ingredients. N-methyl pyrrolidone is listed under California Proposition 65 with certain labeling restrictions. Furthermore, the use of the hydrophobic solvents disclosed in U.S. Pat. Nos. 6,541,516 and 6,187,715 limits the type of active ingredients and the loading depending on the solubility of the active ingredients in the hydrophobic solvent chosen.
Other alternatives are cited in U.S. Pat. No. 4,419,282 which discloses a preferred composition containing N-N,dimethylimidazolone, but does not suggest emulsions in water.
US 20060058191 discloses a pesticide composition featuring an alkoxylated alcohol. Alkoxylated alcohols can provide residual alkylene oxide which is undesirable for health and environmental concerns.
However, it is desired to look for options which are environmentally safe and approved and compatible with the actives of interest. A need therefor exists for alternative methods of dispersing of hydrophobic actives and/or water insoluble film forming polymers, which are particularly used in agricultural fields.
Accordingly, it is an object of this invention to provide a matrix composition for new and improved stable micro-emulsion concentrates which does not require N-alkyl pyrrolidones and/or alkoxylated alcohols in concentrates containing a high loading of different active ingredients. Such compositions are stable upon dilution with water, and which have a relatively long shelf-time, without significant separation or precipitation.
Accordingly, it is one of the objectives of present invention to provide substantially stable homogeneous, water emulsifiable matrix composition which is essentially free of alkyl pyrrolidones and alkoxylated alcohols.
The invention relates to a matrix composition for emulsifiable concentrates containing a desired hydrophobic active or mixtures thereof, and, more particularly, to a matrix with no N-alkyl pyrrolidone including a N,N dialkyl(C1-C4) long chain (C8-C30) acid amide, preferably N,N dialkyl(C1-C2) long chain (C8-C16) acid amide, most preferably N,N dimethyl long chain (C8-C12) acid amide, optional co-solvent like Vegetable oils, ketones, hydrocarbons, esters, ethers, lactones, alcohols, polyols and others capable of solubilizing the active ingredient and preferably with low solubility in water. Additionally, emulsifiers compatible with the solvent system where the chosen emulsifiers are homogeneous with the solvent without any separation during storage under the ambient conditions.
More particularly, the present invention provides an emulsifiable matrix composition for delivery of hydrophobic actives comprising (i) a long chain substituted amide; (ii) a surface active agent; and (iii) optionally, an organic diluent.
The matrix composition of the present invention can be used as a coating for substrates, such as wood, metal, glass, growing crops, soils and the like; as an adjuvant to enhance crop protection and yield and is compatible with several crop protection concentrates especially on dilution in water at use level. The matrix provides a water resistant film on application to surfaces, especially growing crops; rain-fastness during the crop growth; effective enhancement in the crop protection against the pathogen or pests like fungicides and insecticides and herbicides; increased yield of the crop; and is capable of being used as a granulating fluid to produce water-dispersible granules with the adjuvant incorporated.